The only problem I have with this "improvement" from singh grooves is all the testimonials I read, the people had done other things along with it, resurface head, valves, tune-up's, etc. Who is to say these grooves did the improvement or the repairs they did.
I say if it won't cause detonation go for it. I would just round the corners slightly to reduce a "glow plug" affect.
Wouldn't this also lower compression? thus power, also would this not cause slower, incomplete combustion in a correctly designed head?
I love the way they strip, rebuild, retime and adjust mixture and the grooves made all the difference
I've been very suspect that the gooves do much. You are eliminating some of the squish areas that are designed to push the mixture toward the sparkplug and raising surface area of the combustion chamber.
I've never seen any honest dyno tests with emission tests on A-B comparisons without any other mods. I would also believe that if there is merit to them, that their size, depth, location, and angles would be extremely important and that merely hacking away with a dremel tool would never acheive the proper results. It would be like having a port grinder and guessing on how to modify your intake ports for more horsepower. Most of the time, you'd be making them worse then any improvements.
I beat up on Mr.Singh pretty good and out of common decency have "dug in" a little to see if there was more to his grooves.My 700+ page textbook on I.C. Engines had little in the INDEX, however I did find data scattered throughout the book and have amended the index for the future.------------------------- While I'm not vindicating Mr.Singh,there is a logic to the argument,however the text contradicts itself.Here's the deal.-------------------------------------- In 1923,Sir Harry Ricardo,England,received a patent for a "turbulent chamber" design for combustion chambers for an L-Head (flathead) engine.The design induced high turbulence near the end of the compression stroke.The turbulence helped scour the mixture close to the chamber walls,creating a more homogeneous mix,knock was reduced with the piston close to the head.Quench space was small,if autoignition occurred,it would have less impact, as end gas mass was small.End gas was cooled by proximity to cooler walls,spark plug was centrally located near the hot exhaust valve to reduce flame path and speed combustion.---------------------------- The design allowed for higher compression ratios without destructive detonation knock.----------------------------------- Combustion flames can be "laminar" or "turbulent".Laminar flames occur inside bomb calorimeters.Turbulent flames occur inside internal combustion engines.( so I don't understand why Mr. Singh refers to laminar flame with respect to IC engines).--------------------------------- Flame speed can be increased many times with turbulence.Turbulence sweeps unburned mixture into the reaction zone.Also,highly convective currents carry active particles into the unburned region.Turbulence can also arise from flame induction from microscopic explosions.Turbulence increases with engine speed.Combustion time is always shortened by autoignition,gives rise to higher pressure leading to knock.Maximum power is obtained when spark timing is adjusted to point of audible knock.---------------------------------- At the time my book was published,there was no way to quantify turbulent flame velocity,no units to work with,and no way to make tables,showing interrelationships as functions of temp,pressure,composition,etc..No scale had yet been discovered.------------------------- The book makes mention that turbulence,induced on the compression stroke is better than turbulence from the intake stroke,as it does not effect volumetric efficiency.(so far so good for Mr. Singh).------------------------ Here are some points to ponder.From the 1st law of thermo,the mixture cannot have any more energy than the constituent components.And since turbulence is nothing new to combustion chamber and piston design,the efficiency gains from turbulence induced by the grooves requires extraordinary proof.----------------------------- With respect to the Metro engine mods,here are a couple of things to consider.Compression ratios for engines are determined on a basis of engine friction.Compression ratio is a "weak" variable as associated with fuel economy.A 10% increase in compression ratio yields only a 2.3% increase in mpg.Increasing the CR also aggravates the formation of both NOx and HC emissions,requires spark timing to be retarded,which leads to extra engine heat,which requires a bigger or faster fan,and larger radiator.Starting requires more power,the engine requires higher octane.--------------------------- In addition,Tetra ethyl lead,formerly used in high compression engines was believed to create a catalytic effect at the combustion chamber walls,preventing the formation of free radicals and peroxides.Today,without TEL,someone else will have to tell us if current octane enhancers serve the same function.I don't have a clue! Altering an engine from factory specs can defeat the emission controls,potentially releasing CO,alcohols,aldehydes,ketones,phenols,acids,esters ,ethers,epoxides,and other oxygenates besides peroxides.------------------------------- Finally,in some cars with automatic transmissions,the engine can never be loaded to the point of explosive detonation,as the trans simply downshifts to reduce the load,something the Metro would not have available(yes?).------------------So it looks like there are kernels of truth to the premise of the grooves,I just don't know what potential gains can be expected if any,and the article is very subjective and not really loaded with useful quanta.Interesting though!
[QUOTE=bbjsw10;59333]The only problem I have with this "improvement" from singh grooves is all the testimonials I read, the people had done other things along with it, resurface head, valves, tune-up's, etc. Who is to say these grooves did the improvement or the repairs they did.
QUOTE]
That's the same thing I thought, initially at least. I think I looged on to the site and was able to view more things inside... I've never received any spam or solicitations as a result. I read where one guy at least, compensated for groove volume by flycutting the head slightly. Then reading further, some guys simply flycut the head more, under the assumption the grooves are an "enabler" that allow the engine builder to run slightly higher than normal compression with no detonation. Slightly higher than normal compression definately give better cylinder filling and more power. More power per pulse can result in a more efficient use of the fuel you feed the engine.
I can't recite combustion theory paragraph and verse like some can here, but I have been motivated to play with and better understand combustion chamber shape in race engines. A faster burn means less timing lead (advance) is needed, a good thing. Tightening the 'deck' (reducing the clearence between the quench area of the head and piston) on a normally aspirated wedge head design always seems to produce more power, irrespective of compression ratio. On a supercharged engine, tighening the deck has little effect. I believe the tight deck increase turbulance and charge mixing just before ignition.
So, might those low-tech grooves cause 'jets' of air fuel mixture to futher enhance mixing just before ignition? Again, the guy isn't selling anything, so what's the motivation for telling big fish stories? I'm not sure, but I wouldn't use the old "Then whay aren't the automove manufactures all using if its so good" argument. Many large manufacturers have the 'not invented here' mentality, GM had been know for that line of thinking, for instance (not sure about today).
It seems to me there are enough guys here who tinker, that someone objective has played with this idea. You know, layed hands on hardware... or grooves as it were.
I've tested the SGs in a four cylinder SOHC engine with crossflow parallel 2-valve bathtub chambers:
I made lots of modifications in parallel with the SGs, so I can't scientifically prove anything. However this I can say:
- Oil remains cleaner beyond belief. Even the running-in oil (usually black after 50 miles of bedding fresh rings) remained clean.
- No trace of pinging, in spite of compression raised from 9.2:1 to 11.0:1. Not even lugging uphill flat throttle in summer with low octane gasoline (this I chalk to the grooves, my favourite benefit from them).
- Smoother idle.
- No tremble accelerating from 1200 rpm in fifth gear.
- Fuel consumption improved a ~15% (this due also to higher CR and the other mods).
As I see it, the grooves most definitely do not harm, and very probably do a noticeable amount of good, particularly by allowing higher CR without pinging.
I am putting together a 1 liter for my wife's Metro right now, and I am going to try the grooves. Unfortunately, I bought the car with most of #3 piston in the pan, so I won't have any data to compare. I found a post that backs up most of TELVM's claims, especially the reports on oil cleanliness - Link is under post. BTW excellent work, TELVM.....that is probably one of the best looking SG jobs I have seen. I'll post what I find out after I put some miles on it.
The data and anaylis in the second pdf don't seem to agree.
Look at the HP rating through out the range and the non grooved head is almost always higher sometimes dramatically.
The testing was also flawed because the data on combustion chamber size is smaller for the grooved head. If that is correct the grooves must be destroying the combustion process to lose that much HP.
I only skimmed the report and noticed those.
Today
Other popular topics in this forum...
